But Nowak's analysis points to Facebook actually seeing strong daily active user growth this quarter for 18- to 24-year-olds, the demographic most likely to be pulled away by Snapchat's disappearing messages and new cartoon avatars.

He also believes that the ratio of its daily active to monthly active users — which is the best regular measure Facebook gives on how engaged its audience is — will continue to rise and even hit its largest increase since Q1 2015.

"This higher engagement leads to more ad impressions and higher overall monetization as we lift our ad revenue estimates by ~1% in 2016 and ~2% in 2017," Nowak wrote.

Although Nowak admits that he's seen mixed data about how much time users are spending on Snapchat versus Facebook, the projected increase in engagement has him pegging Facebook's Q2 profits between 2 and 8% higher than the rest of Wall Street.